Optimization of Process Parameters for Friction Stir Spot Welding Using Dissimilar Metals

Author(s):  
Pitala Adithya ◽  
B. D. Y. Sunil ◽  
C. Labesh Kumar
2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Kai Xu ◽  
Shu-quan Zhang

Friction stir welding (FSW) is the most popular and efficient method for solid-state joining of similar or dissimilar metals and alloys. This technology is mostly applied in aerospace, rail, automotive, and marine industries. In order to reduce the weight of special auto parts, friction stir spot welding (FSSW) was proposed by some researchers for the connection of steel-aluminium dissimilar metals. However, the steel-aluminium joints welded by FSSW are prone to brittle fracture and have lower shear load although they have high mechanical connection strength. The friction stir spot welding brazing process integrates the brazing effects with the friction welding effects by the addition of solder. A study of FSSW of DP590 and 6061 with the filler metal added was carried out in this paper. The orthogonal test was performed to optimize the process parameters in order to achieve the best shear load of the joint. The shear strength of the joint was studied by the shear test. The fracture morphology was investigated by optical microscopy (OM), scanning electron microscope (SEM), and energy dispersive spectrometer (EDS). The results showed that the shear load of the joint could reach 13.239 kN when the rotating speed, depth, and residence time of the mixing head were 1000 r/min, 0.2 mm, and 90 s, respectively. The aluminium-zinc solder added could well wet the interface between aluminium and steel and promote the metallurgical bonding, thereby improving the shear load of the joint. The temperature field of DP590/6061 FSSW process was simulated by ANSYS software to verify the rationality of the optimal process parameters. The simulation results were confirmed to be basically consistent with the data measured by the thermocouple.


2014 ◽  
Vol 622-623 ◽  
pp. 557-566
Author(s):  
G. D’Urso ◽  
Claudio Giardini

A study was performed to evaluate how the Friction Stir Spot Welding process parameters affect both the thermal distribution in the welding region and the welding forces. An experimental campaign was performed by means of a CNC machine tool and FSSW lap joints on AA6060-T6 aluminum alloy plates having a thickness of 2+2 mm were executed. Five thermocouples were inserted into the samples at a specific distance from the specimen center. A set of tests was carried out by varying the process parameters, namely rotational speed, axial feed rate, plunging depth and dwell time. Axial welding forces were also measured during the execution of the experiments by means of a piezoelectric load cell. The experimental data collected were used to set up and to validate a simulative model of the process. In particular, a 2D FEM model was set up using the commercial code Deform 2D. A 2-dimensional FEM code was preferred in order to guarantee a very simple and practical model able to achieve results in a very short time. Since it is not possible to simulate the rotation of the tool in a 2D configuration, a specific external routine for the calculation of the developed thermal energy due to the friction between tool and workpiece was set up and implemented into the code starting from the local pressure distribution along the contact area.


Author(s):  
L Fratini ◽  
A Barcellona ◽  
G Buffa ◽  
D Palmeri

The results of an experimental study on friction stir spot welding (FSSW) of AA6082-T6 are reported. In particular, process mechanics is highlighted and joint strength is considered in relation to varying the most relevant process parameters. Furthermore, the results obtained are compared with those derived from the application of traditional mechanical fastening techniques such as clinching and riveting. In this way the effectiveness of FSSW is highlighted.


Author(s):  
Kai Chen ◽  
Xun Liu ◽  
Jun Ni

This paper studies a friction stir spot welding (FSSW) process that has been successfully applied to join aluminum alloy 6061-T6 to transformation-induced plasticity steel (TRIP) 780/800 steel. Cross sections of weld specimens show the formation of a hook with a swirling structure. A higher magnified scanning electron microscope (SEM) view of the swirling structure with energy dispersive X-ray spectroscopy (EDS) analysis reveals that it is composed of alternating thin layers of steel and Al–Fe intermetallic compounds (IMCs). To check the effect of different process parameters on the weld strength, the effects of tool plunge speed and dwell time were studied through the design of experiments (DOE) and analysis of variance (ANOVA) method. It shows that dwell time is a more dominant parameter in affecting the weld strength than plunge speed. Furthermore, investigation of failure using a lap shear tests reveals that cross nugget failure is the only failure mode. It also shows that cracks are initiated in the swirling structure at the tensile side of the weld nugget. After failure, a cleavage feature can be observed on the fractured surface.


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